Combine

ABSTRACT

The combine has a threshing cylinder, upper and lower sieves and a recovery sieve all located in the upper part of the casing, with the grain bin below. A fan is located forwardly of the lower sieve. The upper and lower sieves are vibrated with an orbiting motion which cooperates with the air stream from said fan to separate grain from the threshing mix on the sieve surface. The upper and recovery sieves have fish backs which maintain the straw in a bed above the sieve surface. The air stream blows the chaff up into the straw bed of the upper sieve. A dam between the upper and tailings sieve controls the depth of the straw bed. Tailings and clean grain from the recovery sieve are returned to the threshing cylinder and pass by a window in a duct so the operator can monitor the effectiveness of the sieve mechanism.

United States Patent Mathews 1 1 Sept. 11, 1973 [54] COMBINE 3,472,23510/1969 Van der Lely 130/27 R M' [76] Inventor: Bernard 0. Mathews, Po.Box 70, 93995 7/1965 130/27 R Crystal Lake, 111. 60014 PrimaryExaminer-Antonio F. Guida 1 1 Flledi 1971 Att0rneyFoster York et a1.

[21] Appl. No.: 186,053

Related US. Application Data [63] Continuation-in-part of Ser, No,132,727, April 9, 1971, which is a continuation-impart of Ser. No.818,295, April 22, 1969, Pat. No. 3,606,026,

[52] US. Cl. 130/24, 130/26 [58] Field of Search 130/26, 22 R, 24,

130/27 R, 27 E, 27 F, 27 HF, 27 Z [56] References Cited UNITED STATESPATENTS 3,049,129 8/1962 Mark et al. 130/26 1,884,114 10/1932Moroney.... 130/24 1,917,536 7/1933 Mclntire 130/24 1,202,762 10/1916Kranich 130/26 1,210,571 1/1917 Welty ..-130/26 2,937,647 5/1960 Allenet a1. 130/24 2,612,742 10/1952 Heth 130/27 R 57 ABSTRACT The combinehas a threshing cylinder, upper and lower sieves and a recovery sieveall located in the upper part of the casing, with the grain bin below. Afan is located forwardly of the lower sieve. The upper and lower sievesare vibrated with an orbiting motion which cooperates with the airstream from said fan to separate 1 grain from the threshing mix on thesieve surface. The

15 Claims, 10 Drawing Figures PATENTEUSEPI 1191a sum 2 0F 3 m an mqmm wcml dug UUDHWfl UD HE UU UUUUDUU UUDHQU COMBINE This application is acontinuation-in-part of my copending application, Ser. No. 132,727,filed Apr. 9, 1971, which in turn is a continuation-in-part of my thencopending application, Ser. No. 818,295, filed Apr. 22, 1969, now US.Pat. No. 3,606,026 granted Sept. 20, 1971.

This invention relates to a combine for harvesting wheat and othergrains, including com.

In the usual combine now being marketed, the chaff and grain, as well asshort straws and other particles, are shaken out of the straw bed bymeans of straw walkers, and delivered to the chaffer sieve by a returnpan. The separation which takes place at the sieve surface is that ofblowing the chaff away from the sieve and removing the grain through thesieve openings. Occasionally, if the bed of chaff on the sieve is thick,the thickness of the bed prevents proper blow off of the chaff, thusinterfering with the separation and causing some of the chaff and grainto go into the tailings recovery portion of the grain separatingmechanism.

The straw walker, having a separate drive, represents a considerableportion of the cost of the grain separating mechanism.

According to my invention, I eliminate the separate straw walkermechanism, and the separating action essentially is a blowing of thechaff up into or through the straw as contrasted with the aformentionedprior art arrangement in which the separating action is essentially theshaking out of the chaff and of the grain from the straw.

Furthermore, the air stream tends to float or fluidize the straw bed.This floating or fluid bed action is preferably accompanied by a motionof the sieve which has a substantial vertical component, one type ofsuch motion being the orbiting motion described in my aforesaidcopending applications. The rate of motion of the sieve is sufficientlyslow that without flotation by the air stream or the push of materialbeing added to the front of the sieve, the progress of the threshing mixalong the sieve is very slow, both for the grain and for the straw.

The combination of the air stream and the vertical motion maintains thestraw loose so as to promote the shaking out of the grain and chaff.

However, one difficulty encountered in this type of separation is thatif the force of the air stream over the sieve area is not uniformlydistributed, the air stream tends to concentrate in areas where the bedof mix is thin or non-existent. Then proper separation does not occur atother parts of the sieve area where the bed is thicker because ofinsufficient air. Where substantially all of the air escapes through abypass, the condition can be referred to as a blow out.

According to my invention, I provide a dam which tends to build up thebed thickness to the extent where air stream localization and blow outdoes not occur. Thus, there is disposed across the path of the airstream a sufficient amount of straw as to serve as a porous barrier andair flow equalizer in order to permit the separating action to takeplace.

By eliminating the straw walkers, I also increase the residence time ofthe straw in the sieve zone, that is, over the sieve, in inverse ratioto the harvesting rate so that there is greater opportunity for theresidual grain to be dropped out of the straw at lesser harvestingrates. That is, as the amount of material harvested per minutedecreases, the residence time increases.

I have also found that the separating action is improved if the uppersieve is provided with fishbacks or fins having rearwardly aggressiveteeth which maintain some of the straw, and particularly the longerpieces, above the mix which lies directly on the surface of the sieve.The latter I refer to as the surface bed, whereas the straw which rideson the fins, I refer to as the straw bed. The gap between the straw bedand the surface bed permits a more efficient grain separation because itprovides more room for the chaff to acquire the upward motion impartedto it by the air stream.

One advantage of the present arrangement is that when feeding of mix tothe sieve is discontinued, as when making a turn at the end of a field,the straw bed remains for a short period, such as one-half minute to aminute or two with the result that the separation on the sieve surfacecontinues without blow out. In other words, the straw does notimmediately walk back along the fins and climb over the darn so as toallow the escape of air.

Also, when a heavier charge of mix is fed onto the bed, the rate of flowover the dam is increased almost immediately. Therefore, the variouselements cooperate to maintain a rate of straw flow which is about equalto the rate of harvesting, and in which the thickness of the straw bedis either substantially uniform, or else does not decrease below acertain minimum with any degree of rapidity.

In this connection, my invention also provides improved means forfeeding the straw positively to the sieve so as to maintain the rate ofstraw flow.

My arrangement also provides a recovery or scalping sieve which recoverswhatever small percentage of the grains that may be entrapped in thestraw bed and not removed in the sieve zone. According to this aspect ofmy invention, I provide means for visually monitoring the amount ofgrain recovery so that this information can be used in regulating thetravel speed of the combine.

Furthermore, with the present arrangement which eliminates theconventional straw walkers, it is possible to eliminate also the beaterand stripper which are usually employed in conjunction with thethreshing cylinder.

The particular separating mechanism above described is particularlysuitable for the arrangement disclosed in which the separating mechanismis located above the grain bin for the reason that the elimination ofthe conventional straw walkers permits a corresponding reduction in theheight of the combine, which is of the order of a foot or two.

Also, in my arrangement in which the grain bin is located directlybeneath the grain separating mechanism, I eliminate the use of the cleangrain elevator which is required when the grain bin is located above theseparating mechanism. This reduces the proportion of broken grain, acertain amount of broken grain being unavoidable wherever elevators oraugers are used.

Other objects, features and advantages will become apparent as thedescription proceeds.

With reference now to the drawings in which like reference numeralsdesignate like parts:

FIG. 1 is a side elevation of a combine embodying my invention, aportion of the side wall being removed, and some of the elements beingshown diagrammatically;

FIG. 2 is a plan section of FIG. l taken along line 22 of FIG. 1;

FIG. 3 is a transverse section of the upper sieve taken along line 33 ofFIG. 2;

FIG. 4 is an enlarged plan view of a portion of the upper sieve takenalong line 4-4 of FIG. 3;

FIG. 5 is a section taken along line 5-5 of FIG. 4;

FIG. 6 is a detailed vertical section showing the dam and itsrelationship to adjacent parts;

FIG. 7 is a vertical section taken along line 77 of FIG. 6;

FIG. 8 is a side elevation of the upper sieve, a portion of the lowersieve, and the orbiting mechanism for driving same;

FIG. 9 is a vertical transverse section taken along lin 99 of FIG. 8,and

FIG. 10 is a diagrammatic elevation of a modified sieve drivingmechanism.

FIG. 1 shows a combine 10 which includes a horizontal frame 11, twofront wheels 12 and a rear wheel 13. An operators cab 14 is mounted atthe front end of the frame 11, and a casing 15 is mounted on the framerearwardly of the cab, the grain threshing mechanism 16 and separatingmechanism 17 being contained within the casing 15. A grain bin 18extends downwardly from the frame 11 between the front and rear wheels12 and 13, as shown in FIG. 1. A suitable internal combustion engine 19is mounted at the rear end of the frame 11.

The combine also includes a feeder pan 45 which bridges the gap betweenthe threshing mechanism 16 and the separating mechanism 17, and arecovery and recycling mechanism 70 located back of the separatingmechanism 17.

Extending diagonally upward from beneath the cab is a feeder conduit 20which communicates with the upper front end of the casing 15. The lowerend of the feeder conduit terminates in a header mount 21 on which aheader 22 can be removably mounted for harvesting a particular type ofgrain or crop. A slat type elevator 23 is disposed within the feederconduit 20 and extends from the grain head 22 up to the threshingmechanism 16 which is located in the upper front portion of the casing15. The threshing mechanism comprises a rotatably mounted threshingcylinder 24 and a concave 25 cooperating therewith. A removable verticalplate 26 is disposed forwardly of the threshing cylinder 24 and extendsdownwardly into proximity with the upper pulley of the slat typeelevator 23 to prevent carry around of harvested crop and to preventdown draft in the upper front portion of the feeder conduit.

The threshing cylinder 24 is shown as having a discharge zone A beneaththe concave 25 and a discharge zone B, as indicated by arrows in FIG. 1.

Bridging the gap between the elevator 23 and the concave 25 is a rocktrap 27 in the form of a slidable drawer which may be removed through adoor in the casing 15.

The separating mechanism comprises an upper sieve 30 and a lower sieve50. The upper sieve is supported at its rear end by cranks 31 and at itsfront end by links 32, whereas the lower sieve is supported at its rearend by links 51 and at its front end by cranks 52. Cranks, similar tocranks 31 and 52, may be substituted for links 32 and 51 as disclosed inthe aforesaid copending applications, the linkage mechanism to behereinafter described being designed to impart a comparable orbitingmovement to the sieves. A pivotally mounted barrier 33 is located at therear of sieve 30 and comprises a dam. The pivotal mounting permits theelevation of the dam to be adjusted so as to regulate the depth of thestraw bed, as will be hereinafter explained.

The upper sieve 30 also has a plurality of laterally spacedlongitudinally extending fish backs, preferably in the form oflongitudinally oriented vertical strips of sheet metal, referred toherein as fins" 34. The upper edges of the fins are of saw-tooth shape,which is unsymmetrical so as to be aggressive in the rearwardlydirection.

The sieve structure, as shown in FIG. 3, comprises side frame 35supporting a plurality of transversely extending elements 36, which, asshown in FIGS. 4 and 5, are perforated and bent so as to provide ribs37, bottom portions 38 having holes 39 therein, and shelves 40underlying the holes 39. The sieve elements 36 are welded to each otherat 41. The function of these portions of a sieve element is more fullyexplained in my aforesaid copending applications.

Flexible side seals 42 on the side frames 35 engage the side walls 43 ofthe casing 15.

An imperforate feed pan 45 is pivoted at 46 at its rear end to the uppersieve 30 and is supported at its front end by a link 47 which ispivotally connected to the concave 25 by suitable means. The link is animperforate member extending the full width of the machine. The pan 45is also provided with longitudinally extending fins 49 which overlap thefins 34 of the upper sieve 30.

Since the pan is reciprocating back and forth and slopes downwardlytoward the rear, mix from the discharge zone A will slide down the panto the front part of the upper sieve 30. Preferably, the pan 45 isprovided with an irregular surface, shown here as steps 48 which areaggressive toward the rear, to facilitate the rearward movement of themix onto the upper sieve 30.

The structure of the lower sieve 50 comprises an upper frame 53 and alower frame 54. Sieve elements 55, like elements 36, are supported bythe upper frame 53. In front of the sieve elements 55 is an imperforatecleaning pan 56 which also serves as a divider for the air stream.Transverse rods 57 are carried by the lower frame 54 and serve tosupport a canvas barrier 58 having a number of slots 59, as shown inFIG. 2.

Disposed forwardly of the lower sieve 50 is a fan 60 located in asuitable plenum. The fan is preferably of the axial delivery orpropeller type, in which case there are two or more fans spaced side byside to provide an air stream which extends for the full width of thecasing 15. A shutter 61 is disposed between the fan and the lower sievestructure 50. Preferably it is a checkerboard type shutter, as shown inthe aforesaid copending applications, and is made in two independentlyadjustable parts, an upper part 61a and a lower part 6112.

In operation, the air stream delivered by the fan 60 is divided into twoparts by the cleaning pan 56, the upper part passing into the spacebetween the upper and lower sieves, and the lower part passing into thespace between the lower sieve elements 55 and the canvas barrier 58. Aflexible canvas curtain 64 depends.

from the upper sieve, just behind the sieve elements 55 of the lowersieve, and tends to block off the space between the upper and lowersieves 30 and 50. Thus, the major portion of the upper air stream willbe deflected upwardly through the upper sieve. However, the flexibilityof the curtain and the sieve motion cause a certain amount of the upperair stream to bleed into the tailings trough 72.

A second curtain 65 depends from the rear part of the lower sievestructure 50 and cooperates with the canvas barrier 58 to reduce theamount of air blowing through the upper part of the bin 18, thusavoiding eddy currents which might draw chaff down into the grain bin.

As pointed out in the aforesaid copending applications, a major portionof the cleaning is effected at the sieve elements 36; a final cleaningoccurs as the grain drops from the upper sieve to the lower sieve.However, where, as here, there is a heavy concentration of graindropping through the first few sieve elements 36 due to the feed panarrangement 45, the corresponding elements 55 of the lower sieve wouldbecome overloaded with only partially cleaned grain. The cleaning pan 56by interrupting the movement of incompletely cleaned grain into the bin18 subjects the grain to the air stream for a greater period of time asthe grain tumbles back and forth, and finally works its way either overthe front edge or into the first few sieve elements 55.

At other points the grain dropping through the upper sieve passesthrough the lower sieve 50 onto the barrier 58, and thence through theslots 59 into the grain bin 18.

, Any larger particles which may remain on the surface of the lowersieve are subjected to the lower part of the air stream, and tend to bewalked rearwardly to the tailings trough 72 by the combination of theorbiting action and the air stream OPERATION OF SIEVE 30 As the crop isfed by the elevator 23 to the theshing cylinder 24 and carried therebyacross the bars of the concave 25, a substantial portion of the threshedgrains and chaff will drop through the concave at the discharge zone Awhich overlies the front part of the feed pan 45. The reciprocatingmotion of the feed pan will feed this mix downhill and rearwardly to thefront part of the upper sieve 30.

The major portion of the straw is discharged over the rear end of theconcave 25. Located rearwardly of the threshing cylinder 24 is adeflector 66 which is preferably in the form of a flexible or hingedhanging curtain.

The velocity of the straw and other particles thrown out by the cylinderdrives it upwardly into engagement with a steel top plate 69 or with thedeflector 66 from which it rebounds, providing the discharge zone B. The

rear partof the feed pan 45 underlies the discharge zone B, although thedischarge zone B may also overlap the front of the main sieve 30. Thisarrangement prevents the occurrence of any gap in the straw bed at thefront of the sieve 30.

The mix from discharge zone A which .is fed by the feed pan 45 to theupper sieve elements 36 will contain a certain amount of straw aridother particles, as well as the chaff andgrain.

However, the major portion of the straw which is received on the sieveis that which comes over the end of the concave and hence will overliethe feed pan mix. The longer pieces of straw will be caught on the fins34 and thus will be spaced above the mix which rests directly on theelements 36 and which forms the surface bed, indicated by the referencenumeral 62 in FIG. 3.

The straw which is held on the fins forms a straw bed 63 which, in thecase of a heavy crop having a large portion of long straws, representsasubstantial barrier to the air stream traversing the upper sieve. Thisbarrier is a porous barrier and the purpose of the dam 33 is to regulatethe depth of the straw bed and hence the porosity. In a situation wherethe grain is merely topped, the straws may all be comparatively short,with the result that there is very little straw riding on the fins. Herethe surface bed is much thicker because it contains a much greaterproportion of straw and here the elevation of the darn 33 also controlsthe thickness of the straw.

In either event, the major portion of the straw overlies the mix whichpasses through the concave, and the straw is thick enough to providesufiicient resistance to the air blast as to make local thicknessvariations of inconsequential effect in establishing a low resistancebypass in any particular place.

An improved separating action is provided by imparting a substantiallycircular orbiting motion to the upper sieve. The orbiting speed issomewhat slower than the reciprocating speed used in the conventionalClosz sieve. This combination of a relatively slow orbiting movementwith a sieve surface which has transverse ribs 37 or equivalentaggressive surface characteristics cooperates with the air stream toprovide an improved separating action, as pointed out. in the aforesaidcopending applications.

The advantage of the fins 34 is that in a thick crop, the straw ismaintained away from the surface bed 62, leaving a space between themwhich, if not empty, at least represents a much less dense distributionof material. This permits greater action and more efficient chaff fromgrain separation than would otherwise occur in a thick crop.

The provision of the dam 33 therefore assures that sufficient straw willbe available as to avoid localized by-passing of the air stream whichwould destroy the cooperation of the orbiting motion and the air stream.In essence, the arrangement is such that the straw performs an air flowequalizing function.

In the case of a blanked concave in which practically all of thematerial is ejected at the discharge zone B, the straw and the smallerparticles will not be stratified at the time they initially drop ontothe feedpan 45 and the sieve 30. However, the fins 34 cause the totalmix to separate into a surface bed and a straw bed as the smallerparticles are shaken out of the straw.

THE DAM 33 The construction of dam 33 is shown in FIGS. 6 and 7.Oppositely disposed brackets 85, as shown in FIG. 7, are removablysecured to the side frames 35 of the upper sieve at the rear end thereoffor mounting the darn 33. Each bracket has a pivot pin 86. The damitself is formed of perforated sheet metal 88 having side flanges 89. Anangle iron 90 is mounted underneath the sheet 88 at the front edge andextends across the sieve from one pin 86 to another. A sleeve 91 weldedto the angle iron 90 at each side receives the pin 86 so that the sheet88 may be rotated on the pins. The surface of the perforated sheet metalis provided with transverse ribs 92.

A plate 87 on each side frame v35 carries a guide pin 94. The sideflanges 89 are each provided with an arcuate slot 93 which receives theguide pin 94. Suitable nut means may be provided for the guide pins inorder to maintain the dam in its angularly adjusted position. Dependingfrom the sheet 88 is an arcuate plate 95 which extends the full width ofthe sieve and cooperates with the curtain 64 to prevent the loss of airat this point, that is, at the gap between the lower surface of the damand the recovery sieve 71.

In operation, the elevation of the dam can be adjusted according to thenature of the crop to be harvested and the desired thickness of thestraw bed. The orbiting motion of the sieve and the air stream causesthe straw to climb up over the dam onto the recovery sieve 71, but therate of movement of the straw from the upper sieve 30 to the recoverysieve 71 appears to be more a function of the rate at which the straw isforced onto the front of the upper sieve 30, than of the sieve motion.As previously indicated, if the feeding of mix to the sieve isdiscontinued, as when making a turn at the end of a field, the straw beddoes not continue to walk to the rear at the same rate as duringharvesting, but it remains on the upper sieve for a short period such asfrom one-half minute to a minute or two, with the result that theseparation of grains from the mix on the sieve surface continues withoutblowout.

Disposed behind the deflector 66 are one or more flexible or hingedcurtains 67 which tend to prevent dissipation of the straw bed by theair stream, and in the case of a heavy straw bed, serve to maintain thestraw in contact with the fins 34. The top of the casing is in the formof a removable substantially impervious tarpaulin 68 maintained in placeby suitable lacing. This permits easy access to the separating mechanism17.

RECOVERY AND RECYCLING MECHANISM 70 The recovery and recycling mechanism70 comprises a recovery sieve 71 located behind the upper sieve 30 andabove a tailings trough 72. The recovery sieve 71 comprises side frames74 which support a suitable sieve structure having rearwardly aggressivesurface characteristics. The same may be of wire mesh, or perforatedmetal with transverse ribs, or they may be in the form of sieve elements75 similar to the sieve elements 36. The recovery sieve also includesfins 76 similar to the fins 34.

A return pan 77 is located beneath the recovery sieve 71. Suitable meansare provided for driving the recovery sieve 71 so as to shake out of theoverlying straw bed any grains not removed by the upper sieve and fordriving the return pan 77 to cause the grains to slide down the pan 77to the tailings trough 72. The bleed air passing under curtains 64 and65 blows chaff out at the rear.

As shown herein, the side frames 74 constitute extensions of the sideframes 35 so that the recovery sieve 71 is driven with the upper sieve30. The return pan 77 is suitably supported from the lower sieve 50 andmoves therewith. The return pan is provided with forwardly aggressivesteps 78, and is disposed at a very substantial forwardly facingdownward slope to force movement of grains in a direction opposite tothat which is naturally induced by the orbiting motion of the pan, andopposite to the force of the bleed air passing out between recoverysieve 71 and return pan 77.

In addition to the recovery of threshed grains entrapped in the strawbed, any grain heads and other insufficiently threshed particles whichpass over the dam 33, will be recovered through the openings in thesieve elements 75. Such openings may be somewhat larger than theopenings in elements 36. As previously indicated, any tailings walked tothe rear of the lower sieve 50 are also deposited in the auger trough72.

A tailings auger 80 is disposed in the auger trough 72 and feeds thetailings transversely into an elevator pipe 81 (FIG. 2) from which it isconveyed into a duct 82, and then downwardly by gravity through the duct82 and through an opening in the upper wall of the feeder conduit 20 sothat the tailings will be carried back to the cylinder 24 by the slatsof the elevator 23.

Due to the fact that my grain separating mechanism has a definitecapacity or maximum separating rate, depending on the nature of the cropand the air adjustment, which is independent of the harvesting rate asdetermined by the forward travel speed of the combine, the amount ofgrain recovered from the recovery sieve 7l affords an indication as towhether the combine is travelling too fast. Thus, it is possible toutilize the recovery and recycling mechanism 70 as a monitoring systemfor judging the amount of grain lost over the end of the recovery sieve71.

The duct 82 has an opening or window 83 therein, located right behindthe operators cab 14 and visible to the operator through a glass window,not shown.

By observing through the window 83 the amount of grain contained in thetailings, the operator is able to judge the effectiveness of theseparating mechanism, and can regulate the forward travel speed of thecombine accordingly.

With minimal experience, the operator is able to tell what amount offree grain in the tailings represents an end loss. Thus, in going from athin crop into a thick crop, the travel speed can be regulated to avoidend loss.

DRIVE MECHANISM FOR SIEVES The orbiting mechanism is shown in FIGS. 8and 9. Upon the horizontal frame 11 there is mounted a rock lever 100.Its fulcrum is in the form of a bearing 101 which engages a suitablepivot pin (not shown) carried by the frame member 11. The front end ofthe rock lever is pivotally connected to the link 32 which extends downfrom the side frame 35; the construction being duplicated on the otherside of the grain separating mechanism. The rear end of the rock lever100 is pivotally connected to a link 102 which extends downwardly fromthe lower sieve 50. The link is shown as being connected to the lowersieve at a vertical member 103 that connects the upper and lower framemembers 53 and 54.

A second rock lever 104 is supported by a pivot pin (not shown)extending from a suitable structural member of the side wall, theconstruction being duplicated on the other side of the grain separatingmechanism. The fulcrum is in the form of a bearing 105 which engagessaid pin. The front end of the rock lever 104 is pivotally connected tothe link 51 which extends downwardly from the lower sieve 50 and therear end of the rock lever is pivotally connected to the side frame 74of the recovery sieve 71 by link 106. As viewed in FIGS. 1 and 8,clockwise rotation of the crank 31 will impart circular motion to theupper sieve 30 at this point. This circular motion will be transmittedthrough the linkage 106, 104, and 51 to the rear end of the lower sieve50.

Similarly, clockwise rotation of the crank 52 will impart orbitingmotion to the front end of the lower sieve 50, which will be transmittedthrough the linkage 102, 100 and 32, to the front end of the upper sieve30.

Thus, the upper and lower sieves, each being supported at one end by acrank and at the other end by a link, are caused to move in an orbitingmovement in opposed phase relationship. That is, as the upper sievemoves upwardly and rearwardly, the lower sieve will be moving downwardlyand forwardly, and vice versa. The sieves counterbalance each other dueto thisopposed movement thus considerably reducing the vibrationtransmitted by the sieve to the casing 15. Also, the be]- lows action ofthe oppositely moving sieves provides a pulsation of the air stream asit moves upwardly through the upper sieve which assists in theseparating action.

The two cranks 52 are mounted at opposite ends of a shaft 107 whichextends across the casing from one side wall to the other, the ends ofthe shaft being mounted in bearings 108 in the side walls 43 of thecasing 15, as shown in FIG. 9. The lower sieve 50 has a bracket 109which carries bearing blocks 110 which engage the eccentric crankportion 111 of the crank 52. Thus, rotation of the shaft 107 will causeorbiting movement of the lower sieve 50. A sprocket 112 is secured tothe shaft 107 externally of the side wall 43 of the casing 15, and isconnected by a chain 113, to a similar sprocket affixed to the shaft ofcrank 31 so as to maintain the 180 phase relationship. The constructionof crank 31 is the same as that of crank 52, and will not be repeated.The shaft 107 is driven through a suitable chain and sprocket at the endopposite to that shown in FIG. 9.

In the embodiment shown, the eccentricity of the crank 52 is 1 inch,providing a 2-inch throw for the lower sieve 5th, and the eccentricityof the crank 31 is 2 inches, providing a 4-inch throw for the rearportion of the upper sieve. The fulcrum 105 is so located that the4-inch vertical throw of the link 106 provides a 2- inch vertical throwfor the link 51. Thus the vertical movement of both the front and backportion of the lower sieve is 2 inches.

The location of fulcrum 101 is such that the 2-inch vertical movement ofthe link 102 causes a Zia-inch vertical movement of the link 32. Thusthe front end of the upper sieve 30 has a 2% inch throw, whereas theportion of the recovery sieve 71 immediately above the crank 31 has a4-inch vertical throw. The horizontal movement of all parts of theassembly 30-71 will be 4 inches. Thus the front end of the upper sieveorbits in an elliptical path having a 2% inch vertical throw and a4-inch horizontal throw, and the extent of the vertical throw increasesas one approaches the rear end of the upper sieve, the throw at thispoint being about 3.7 inches. The advantage of this arrangement is thatit is possible to provide a greater vertical throw for the recoverysieve 71 than the average vertical throw of the upper sieve 30, eventhough they are rigidly connected to each other by the integral sideframes 35-74. The throw at the rear end of sieve 71 is 4.7 inches.

It has been found that a speed of as low as 160 r.p.m. for the cranksresults in satisfactory separating action, providing the desiredweightless action over the major portion of the upper sieve 30, andproviding a greater agitating action for the recovery sieve 71 which iseffective in shaking the grains out of the straw bed.

The motion of the sieve can also be a linear or arcuate reciprocatingmotion provided the reciprocating motion embodies a substantial verticalcomponent. The vertical component of the sieve motion is essentially aharmonic motion, and the frequency of the reciprocating motion issomewhat slower than that generally applied to a Closz type sieve.

An example of mechanism for imparting reciprocating motion to the sievesis shown in FIG. 10. The sieves 30 and 50 are supported at one end by acommon link pivoted at 116. -A crank 117' rocks the link 115 through aconnecting rod 118. A similar link supports the other end of each sieve.

In the case of either orbiting motion or reciprocating motion, thefrequency in cycles per second (or speed in r.p.s.) should be equal to KV a/2 where a is the magnitude of the vertical component of the sievemotion in inches, and K is a numerical coefficient having a value ofbetween 3.0 and 4.5, as indicated in aforesaid Ser. No. 132,727.

It is believed that the desired results are best obtained when thevertical component of the sieve motion is an inch or more and thefrequency is less than substantially 250 c.p.m. as contrasted, forexample, with the much higher frequencies used in vibratory settling andfluidization, such as 60 Hz with amplitudes of the order of hundredthsor thousandths of an inch.

In the example given K has a value of substantially 3.0 at the front ofthe sieve 30, and 3.6 at the rear. The low K value at the front of thesieve reduces the walking tendency so as to increase the residence time.The weightless characteristic at this speed range contributes to thefluid or floating action of the straw, but the speed is sufficientlyslow as to prevent the grains adjacent the sieve surface from remixingwith the overlying mix and straw.

The greater theK value, the greater the tendency to separate the grainfrom the straw by agitation. However, where the major portion of thegrain from straw separation is caused by the stratification due to thedischarge zones A and B, or by the use of the fins 49 and 34, or byboth, it is possible to use frequencies corresponding to the lower Kvalues.

It should be noted that at the lower K values, the advance of the strawbed is believed to be due largely to the longitudinal displacement ofthe straw at the front edge of the sieve 30 by the action of the feedpan 45. The downward and rearward slope of the steps 48 and of the teeth49 causes a positive feeding action into the previously deposited strawand consequent displacement thereof. It will be noted that the link 47provides a largely horizontal reciprocating motion for the feed pan 45.The mounting of the feed pan 45 between the link 47 and the sieve 30 andits connection to the latter provides a continuous path for the mix fromthe discharge zone A to the upper sieve 30. v

The canvas barrier 58 can be made in two or more separate partsseparated by a transverse gap 59a, as shown in FIG. 2, thus providing anadditional opening for grain dropping into said bin.

Suitable unloading means 120 are provided for emptying the grain fromthe bin 18 into a truck, as shown in FIG. 2.

The disclosure of my aforesaid copending applications, Ser. Nos. 818,295and 132,727 are hereby incorporated by reference into this application,insofar as said disclosures are consistent with the teachings of thisapplication.

Although only preferred embodiments of my invention have been shown andillustrated herein, it will be understood that various modifications andchanges can be made in the constructions shown without departing fromthe spirit of my invention, as pointed out in the appended claims.

I claim:

1. A combine comprising threshing mechanism having a mix discharge zoneand a strawv discharge zone, a main sieve located to receive the entireoutput thereof including mix from said mix discharge zone and straw fromsaid straw discharge zone with said straw overlying said mix, air streamproviding means, said main sieve being disposed across the air streamprovided by said air stream providing means with said air stream passingupwardly'through said sieve, a recovery sieve located behind said mainsieve and connected thereto, means vibrating said main sieve and saidrecovery sieve in an orbital path, dam means located between said mainsieve and said recovery sieve and including a transverse elementextending for substantially the full width of said main sieve andoperative to preserve the continuity of the bed formed by the strawoverlying the mix on said main sieve, said straw bed providing a porousbarrier traversed by said air stream.

2. A combine as claimed in claim 1 which includes means for positivelyfeeding said output onto said main sieve and into the edge of the strawoverlying same to displace same rearwardly.

3. In a combine as claimed in claim 1, a feed pan extending between saidthreshing mechanism and said main sieve, said feed pan being downwardlysloping to the rear and being pivotally connected at its rear end to thefront end of said main sieve, link means supporting the front end ofsaid feed pan for substantially horizontal reciprocating movement,whereby the orbital movement of said main sieve will cause the rear endof said feed pan to move with an orbital motion, said feed pan beingimperforate.

4. A combine as claimed in claim 1 in which said main sieve has aplurality of longitudinally extending transversely spaced fins mountedon the upper surface thereof, said fins having rearwardly aggressiveteeth formed on their upper edges for engaging at least a portion ofsaid straw to maintain same spaced above the surface of said main sieve.

5. A combine as claimed in claim 1 in which said means for vibratingsaid sieve in an orbital path includes means for imparting to said sievean orbital motion having a substantial vertical component, the magnitudea of which in inches bears the following relationship to the frequency Fin cycles per second of said vibrating means:

where K is a numerical coefficient having a value of from 3.0 to 4.5.

6. A combine as claimed in claim 1 in which said transverse element ispivotally mounted on said sieve, and means to retain said element in anadjusted angular position to control the depth of said straw bed.

7. A combine as claimed in claim 1 in which said transverse element isprovided with rearwardly aggressive surface characteristics tofacilitate the movement of straw thereover.

8. A combine comprising threshing mechanism, a main sieve located toreceive mix from said threshing mechanism, air stream providing means,said sieve being disposed across the air stream provided by said airstream providing means with said air stream passing upwardly throughsaid sieve, a recovery sieve located behind said main sieve, a flexiblebaffle located between said main sieve and said recovery sieve andextending downwardly therefrom so as to cause the major portion of saidair stream to traverse said main sieve and to permit a minor portion tobleed rearwardly into the space beneath said recovery sieve, said majorair stream portion traversing said main sieve to blow the chaff portionof said mix upwardly into the straw overlying same, means for vibratingsaid sieves to promote the withdrawal of grain from the mix overlyingsaid main sieve, and to shake grain out of the straw overlying said mainsieve, said minor air stream portion blowing rearwardly the chaffdropping from said recovery sieve, and means for recycling the graindropping from said recovery sieve.

9. A combine as claimed in claim 8 which includes an operators stationlocated forwardly of said threshing mechanism, said recycling meansincluding a conduit means located adjacent said operators station, andan opening in said conduit means visible to an operator located at saidoperators station for monitoring the amount of grain passing throughsaid recycling means.

10. A combine as claimed in claim 9 in which said recycling means alsoincludes a trough located beneath said recovery sieve, second conduitmeans extending from said trough to an elevated point adjacent saidoperators station, feeder means for feeding unthreshed crop to saidthreshing mechanism, said first mentioned conduit means extendingdownwardly between said elevated point and said feeder means andcommunicating with said second conduit means and said feeder means, andmeans for causing grain to flow from said trough through said secondconduit means and into said first conduit means, past said opening, andinto said feeder means.

11. A combine as claimed in claim 8 in which said main .sieve and saidrecovery sieve are rigidly connected to each other to move as a unit,and in which said means for vibrating said sieves includes means forimparting to said sieves a harmonic motion having a substantial verticalcomponent, the magnitude of the average vertical motion imparted to saidrecovery sieve being greater than the magnitude of the average verticalmotion imparted to said main sieve whereby the shaking motion applied tosaid recovery sieve to shake the grain out of the straw is greater thanthe shaking motion applied to said main sieve.

12. A combine comprising threshing mechanism having a mix discharge zoneand a straw discharge zone, a main sieve located to receive mix fromsaid mix discharge zone and straw from said straw discharge zone withsaid straw overlying said mix, air stream providing means, said sievebeing disposed across the air stream provided by said air streamproviding means with said air stream passing upwardly through saidsieve, a recovery sieve located behind said main sieve, a flexiblebaffle located between said main sieve and said recovery sieve andextending downwardly therefrom so as to cause the major portion of saidair stream to traverse said main sieve and to permit a minor portion tobleed rearwardly into the space beneath said recovery sieve,

dam means located between said main sieve and said recovery sieve toregulate the depth of the straw overlying the mix on said main sieve,said straw providing a porous barrier traversed by said major portion ofsaid air stream and being operative to provide a distribution of saidmajor air stream portion traversing said main sieve which is free fromblow out and sufficiently uniform so as to provide at substantially allportions of said main sieve a separating action in which the chaffportion of said mix is blow upwardly into said straw, and means forvibrating said sieves to promote the withdrawal of grain from the mixoverlying said main sieve and to shake grain out of the straw overlyingsaid main sieve, said minor air stream portion blowing rearwardly thechaff dropping from said recovery sieve.

13. A combine comprising a casing, threshing mechanism located in theupper front part of said casing, separating mechanism located rearwardlyof said threshing mechanism and including an upper sieve and a lowersieve, means vibrating said sieves, feed means located beneath saidthreshing mechanism and extending rearwardly to the front part of saidupper sieve for conveying mix received from said threshing mechanism tosaid upper sieve, air stream providing means including a fan locatedforwardly of said sieves, a grain bin located beneath said lower sievefor receiving grain passing through said lower sieve, a substantiallyhorizontal barrier supported by said lower sieve and located beneathsame and above said grain bin and having openings formed therein topermit the passage of grain therethrough into said bin, and said barrierdiverting the air stream from said fan upwardly through said lower sieveand tending to prevent the establishment of eddy currents within saidgrain bin.

14. A combine comprising a casing, threshing mechanism located in theupper front part of said casing, separating mechanism located rearwardlyof said threshing mechanism and including a sieve, feed means locatedbeneath said threshing mechanism and extending rearwardly to the frontpart of said sieve for conveying mix received from said threshingmechanism to said sieve, air stream providing means including a fanlocated forwardly of said sieve, a plurality of longitudinally extendingtransversely spaced fins integrally mounted on said sieve and havingrearwardly aggressive teeth formed on their upper edges to engage atleast a portion of the straw discharged from said threshing mechanismand maintain said straw spaced above the surface of said sieve, said airstream traversing said sieve upwardly and blowing chaff from the surfaceof said sieve upwardly into said straw, means for vibrating said sievewith a motion having a substantial vertical component to facilitateseparation of the grains and the chaff on the surface of said sieve, andto walk rearwardly the straw overlying said fins at a rate substantiallyequal to the rate at which said straw is received from said threshingmechanism to prevent attenuation of the straw overlying said fins, saidfeed means comprising an imperforate feed pan pivotally connected at itsrear end to the front end of said sieve and vibrating therewith, saidfeed pan also having a plurality of longitudinally extendingtransversely spaced fins having rearwardly aggressive teeth formed ontheir upper edges whereby straw engaged by said feed pan fins will bepositively fed onto said sieve fins.

15. A combine comprising threshing mechanism, separating mechanismlocated rearwardly of said threshing mechanism and including an uppersieve and a lower sieve, said upper sieve receiving the entire output ofsaid threshing mechanism, said output comprising mix including straw,means located beneath said lower sieve for deflecting air upwardlythrough said lower sieve, air stream providing means located forwardlyof said upper and lower sieves,

a portion of the air stream provided thereby passing into the spacebetween said deflecting means and said lower sieve and thence upwardlythrough both of said sieves and another portion passing into the spacebetween said upper and lower sieves and thence upwardly through saidupper sieve,

a recovery sieve located behind said upper sieve and moving therewith,

dam means located on said upper sieve at the rear thereof and forwardlyof said recovery sieve to control the depth of the straw overlying saidupper sieve,

said straw bed providing a porous barrier traversed by said air stream,

means vibrating said upper and lower sieves in an orbital path and inthe same rotative direction but in opposed phase relationship to eachother, and

means for recycling the grain dropping from said recovery sieve.

1. A combine comprising threshing mechanism having a mix discharge zoneand a straw discharge zone, a main sieve located to receive the entireoutput thereof including mix from said mix discharge zone and straw fromsaid straw discharge zone with said straw overlying said mix, air streamproviding means, said main sieve being disposed across the air streamprovided by said air stream providing means with said air stream passingupwardly through said sieve, a recovery sieve located behind said mainsieve and connected thereto, means vibrating said main sieve and saidrecovery sieve in an orbital path, dam means located between said mainsieve and said recovery sieve and including a transverse elementextending for substantially the full width of said main sieve andoperative to preserve the continuity of the bed formed by the strawoverlying the mix on said main sieve, said straw bed providing a porousbarrier traversed by said air stream.
 2. A combine as claimed in claim 1which includes means for positively feeding said output onto said mainsieve and into the edge of the straw overlying same to displace samerearwardly.
 3. In a combine as claimed in claim 1, a feed pan extendingbetween said threshing mechanism and said main sieve, said feed panbeing downwardly sloping to the rear and being pivotally connected atits rear end to the front end of said main sieve, link means supportingthe front end of said feed pan for substantially horizontalreciprocating movement, whereby the orbital movement of said main sievewill cause the rear end of said feed pan to move with an orbital motion,said feed pan being imperforate.
 4. A combine as claimed in claim 1 inwhich said main sieve has a plurality of longitudinally extendingtransversely spaced fins mounted on the upper surface thereof, said finshaving rearwardly aggressive teeth formed on their upper edges forengaging at least a portion of said straw to maintain same spaced abovethe surface of said main sieve.
 5. A combine as claimed in claim 1 inwhich said means for vibrating said sieve in an orbital path includesmeans for imparting to said sieve an orbital motion having a substantialvertical component, the magnitude a of which in inches bears thefollowing relationship to the frequency F in cycles per second of saidvibrating means: F Square Root a/2 K where K is a numerical coefficienthaving a value of from 3.0 to 4.5.
 6. A combine as claimed in claim 1 inwhich said transverse element is pivotally mounted on said sieve, andmeans to retain said element in an adjusted angular position to controlthe depth of said straw bed.
 7. A combine as claimed in claim 1 in whichsaid transverse element is provided with rearwardly aggressive surfacecharacteristics to facilitate the movement of straw thereover.
 8. Acombine comprising threshing mechanism, a main sieve located to receivemix from said threshing mechanism, air stream providing means, saidsieve being disposed across the air stream provided by said air streamproviding means with said air stream passing upwardly through saidsieve, a recovery sieve located behind said main sieve, a flexiblebaffle located between said main sieve and said recovery sieve andextending downwardly therefrom so as to cause the major portion of saidair stream to traverse said main sieve and to permit a minor portion tobleed rearwardly into the space beneath said recovery sieve, said majorair stream portion traversing said main sieve to blow the chaff portionof said mix upwardly into the straw overlying same, means for vibratingsaid sieves to promote the withdrawal of grain from the mix overlyingsaid main sieve, and to shake grain out of the straw overlying said mainsieve, said minor air stream portion blowing rearwardly the chaffdropping from said recovery sieve, and means for recycling the graindroppIng from said recovery sieve.
 9. A combine as claimed in claim 8which includes an operator''s station located forwardly of saidthreshing mechanism, said recycling means including a conduit meanslocated adjacent said operator''s station, and an opening in saidconduit means visible to an operator located at said operator''s stationfor monitoring the amount of grain passing through said recycling means.10. A combine as claimed in claim 9 in which said recycling means alsoincludes a trough located beneath said recovery sieve, second conduitmeans extending from said trough to an elevated point adjacent saidoperator''s station, feeder means for feeding unthreshed crop to saidthreshing mechanism, said first mentioned conduit means extendingdownwardly between said elevated point and said feeder means andcommunicating with said second conduit means and said feeder means, andmeans for causing grain to flow from said trough through said secondconduit means and into said first conduit means, past said opening, andinto said feeder means.
 11. A combine as claimed in claim 8 in whichsaid main sieve and said recovery sieve are rigidly connected to eachother to move as a unit, and in which said means for vibrating saidsieves includes means for imparting to said sieves a harmonic motionhaving a substantial vertical component, the magnitude of the averagevertical motion imparted to said recovery sieve being greater than themagnitude of the average vertical motion imparted to said main sievewhereby the shaking motion applied to said recovery sieve to shake thegrain out of the straw is greater than the shaking motion applied tosaid main sieve.
 12. A combine comprising threshing mechanism having amix discharge zone and a straw discharge zone, a main sieve located toreceive mix from said mix discharge zone and straw from said strawdischarge zone with said straw overlying said mix, air stream providingmeans, said sieve being disposed across the air stream provided by saidair stream providing means with said air stream passing upwardly throughsaid sieve, a recovery sieve located behind said main sieve, a flexiblebaffle located between said main sieve and said recovery sieve andextending downwardly therefrom so as to cause the major portion of saidair stream to traverse said main sieve and to permit a minor portion tobleed rearwardly into the space beneath said recovery sieve, dam meanslocated between said main sieve and said recovery sieve to regulate thedepth of the straw overlying the mix on said main sieve, said strawproviding a porous barrier traversed by said major portion of said airstream and being operative to provide a distribution of said major airstream portion traversing said main sieve which is free from blow outand sufficiently uniform so as to provide at substantially all portionsof said main sieve a separating action in which the chaff portion ofsaid mix is blow upwardly into said straw, and means for vibrating saidsieves to promote the withdrawal of grain from the mix overlying saidmain sieve and to shake grain out of the straw overlying said mainsieve, said minor air stream portion blowing rearwardly the chaffdropping from said recovery sieve.
 13. A combine comprising a casing,threshing mechanism located in the upper front part of said casing,separating mechanism located rearwardly of said threshing mechanism andincluding an upper sieve and a lower sieve, means vibrating said sieves,feed means located beneath said threshing mechanism and extendingrearwardly to the front part of said upper sieve for conveying mixreceived from said threshing mechanism to said upper sieve, air streamproviding means including a fan located forwardly of said sieves, agrain bin located beneath said lower sieve for receiving grain passingthrough said lower sieve, a substantially horizontal barrier supportedby said lower sieve and located beneath same and above said grain binand having openings formed therein to permit the passage Of graintherethrough into said bin, and said barrier diverting the air streamfrom said fan upwardly through said lower sieve and tending to preventthe establishment of eddy currents within said grain bin.
 14. A combinecomprising a casing, threshing mechanism located in the upper front partof said casing, separating mechanism located rearwardly of saidthreshing mechanism and including a sieve, feed means located beneathsaid threshing mechanism and extending rearwardly to the front part ofsaid sieve for conveying mix received from said threshing mechanism tosaid sieve, air stream providing means including a fan located forwardlyof said sieve, a plurality of longitudinally extending transverselyspaced fins integrally mounted on said sieve and having rearwardlyaggressive teeth formed on their upper edges to engage at least aportion of the straw discharged from said threshing mechanism andmaintain said straw spaced above the surface of said sieve, said airstream traversing said sieve upwardly and blowing chaff from the surfaceof said sieve upwardly into said straw, means for vibrating said sievewith a motion having a substantial vertical component to facilitateseparation of the grains and the chaff on the surface of said sieve, andto walk rearwardly the straw overlying said fins at a rate substantiallyequal to the rate at which said straw is received from said threshingmechanism to prevent attenuation of the straw overlying said fins, saidfeed means comprising an imperforate feed pan pivotally connected at itsrear end to the front end of said sieve and vibrating therewith, saidfeed pan also having a plurality of longitudinally extendingtransversely spaced fins having rearwardly aggressive teeth formed ontheir upper edges whereby straw engaged by said feed pan fins will bepositively fed onto said sieve fins.
 15. A combine comprising threshingmechanism, separating mechanism located rearwardly of said threshingmechanism and including an upper sieve and a lower sieve, said uppersieve receiving the entire output of said threshing mechanism, saidoutput comprising mix including straw, means located beneath said lowersieve for deflecting air upwardly through said lower sieve, air streamproviding means located forwardly of said upper and lower sieves, aportion of the air stream provided thereby passing into the spacebetween said deflecting means and said lower sieve and thence upwardlythrough both of said sieves and another portion passing into the spacebetween said upper and lower sieves and thence upwardly through saidupper sieve, a recovery sieve located behind said upper sieve and movingtherewith, dam means located on said upper sieve at the rear thereof andforwardly of said recovery sieve to control the depth of the strawoverlying said upper sieve, said straw bed providing a porous barriertraversed by said air stream, means vibrating said upper and lowersieves in an orbital path and in the same rotative direction but inopposed phase relationship to each other, and means for recycling thegrain dropping from said recovery sieve.